The bacterial colonization of intra-oral hard surfaces in vivo:Influence of surface free energy and surface roughness

The recolonization rate of a tooth surface after perfect cleaning follows an exponential curve with a very slow growth rate during the first 24 h. After 4 days of undisturbed plaque formation, more than 30% of the tooth surface will be covered by plaque. During the night, plaque growth rate is up to 50% less than during the day. Plaque growth pattern was found to correlate closely with irregularities in the tooth surface. A positive correlation exists between the recolonization rate and the substratum surface free energy (sfe). On surfaces with a low sfe the rate of bacterial recolonization is slower and the strength of adhesion on these surfaces is weaker. Moreover, the composition of the plaque depends on the substratum sfe. Low sfe bacteria adhere preferentially to low sfe surfaces (Teflon), and high sfe bacteria prefer high sfe substrata (enamel). The rate of bacterial colonization of intra-oral hard surfaces is positively correlated with surface roughness (sr), as is the speed of plaque maturation. Comparing the effects of sfe and sr on plaque accumulation and plaque composition, sr is found to be more prominent. Preliminary results suggested similar conclusions when subgingival plaque growth was considered. Preventive measures should thus be aimed at lowering the sfe and sr of intra-oral hard surfaces.